The governors who signed the bill are particularly notable, since some are from states represented by Republican senators who are weighing whether to back the bill. Among them: Alaska Gov. Bill Walker (I), who holds sway over Sen. Lisa Murkowski (R-Alaska), a potentially decisive vote.

“We ask you not to consider” the repeal-and-replace bill, “and renew support for bipartisan efforts to make health care more available and affordable for all Americans. Only open, bipartisan approaches can achieve true, lasting reforms,” the governors wrote.

Also among the governors signing the letter: John Kasich (R-Ohio) and Brian Sandoval (R-Nev.).

[New push to replace Obamacare reflects high stakes for Republicans]

Sandoval is now at odds with Sen. Dean Heller (R-Nev.), who is a co-sponsor of the bill, which would give states control over billions in federal health-care spending and enact deep cuts to Medicaid. Sen. Rob Portman (R-Ohio) said Tuesday that he is still weighing whether to support the plan.

The letter comes as the White House is ramping up its lobbying on the bill. Vice President Pence is attending Tuesday’s Senate Republican lunch, where he said he would urge lawmakers to pass the bill.

“This is the moment. Now is the time. We have 12 days,” Pence said he planned to tell Republican senators, according to a White House pool report.

On Tuesday, Pence traveled from New York, where he was attending the annual U.N. General Assembly, to Washington with Sen. Lindsey O. Graham (R-S.C.), one of the bill’s sponsors, in a sign of the White House’s support for the proposal.

Pence said he has also been calling governors and some Democratic senators, including Joe Manchin III (W.Va.), to build support for the bill.